Earth's Water: Groundwater Percentage Quiz and Flashcards

Earth is the only known habitat for life in the universe, with an age of approximately 1/3 of the universe's age.
Earth's core is rich in heavy minerals, with a crust that is relatively lighter, surrounded by a thin layer of breathable air, vast oceans, fertile plains, magnificent mountains, rivers of freshwater, springs, lakes, and underground water reservoirs.
The Earth orbits around a star that provides warmth and energy, but how did our habitat come into existence and what is it composed of?
Approximately 4.6 billion years ago, the Earth formed from the remnants of dead stars, which gathered in massive gas clouds, increasing in density and eventually forming a disk.
Small particles began to clump together, forming larger bodies until they shaped what we today call "planets," a process that took around 10-20 million years and is still not fully understood.
During this time, when our solar system was still small and chaotic, a large body, roughly the size of Mars, collided with our planet, causing a massive shock that could have destroyed Earth if it were larger.
Debris from the Earth was scattered into orbit, forming the Moon, which is the largest moon relative to its planet in the solar system.
At that time, the Earth was closer to hell, constantly colliding with numerous asteroids, filled with oceans of magma, and a toxic atmosphere, but a significant change was about to occur as the Earth cooled.
Water from the Earth's interior rose to the surface, then rained down, only to evaporate again and form clouds, with millions of asteroids bringing more and more water to our planet.
The total amount of water on Earth is roughly proportional to its size, with 71% of the surface covered in water and 29% in land.
97.5% of the water is salty, while only 2.5% is freshwater, with 69% of it in the form of ice and snow, 30% as groundwater, and 1% as surface water, most of which is frozen and only a small portion forming lakes, rivers, and living organisms.
As the Earth cooled gradually, its surface formed a thin crust, but hot rocks beneath the surface still move, causing the crust to shift and break, a process known as "tectonic plates."
These plates are constantly moving, sometimes colliding and forming massive mountains or sinking into the Earth's interior, creating deep trenches.
This process is how the highest point on Earth's surface, Mount Everest, and the deepest point, the Mariana Trench, were formed.
To us, the Earth's mountains and trenches may seem enormous, but if we look at a cross-section of the Earth, we can see how small they are in reality.
The part we stand on is the crust, which is roughly 50 km thick and can vary between 5 and 70 km.
Beneath the crust lies the mantle, a layer of silicates about 2,900 km thick, composed of the upper mantle and lower mantle.
The upper mantle contains different regions, including the lithosphere, which carries the Earth's crust, and the asthenosphere, which is made of less mobile and more stable materials.
The lower mantle reaches the Earth's deep interior, neighboring the outer core.
The outer core is a liquid layer of iron and nickel, about 2,266 km thick, with temperatures ranging from 4,000 to 5,700 degrees Celsius.
At the center of the Earth lies the inner core, a solid ball of iron and nickel with a diameter of approximately 1,200 km, about 70% of the Moon's size and with a temperature similar to the surface of the Sun.
The inner core grows slowly at a rate of about 1 meter per year.
Now, putting this in perspective, the thin layer we inhabit was once part of the molten mantle.
There is also the Earth's magnetic field, an invisible phenomenon that deflects high-energy particles coming from the Sun or other sources, allowing for a stable environment with relatively little radiation impact on Earth.
But what causes this field? In reality, we don't know much about it, only that it's related to the Earth's core, where large amounts of electric currents flow in complex patterns, forming a magnetic field that is stable according to electromagnetic laws.
This system is called a "dynamo," but don't let us deceive you into thinking we have a complete understanding of this phenomenon.
Speaking of astonishing facts, what about the air surrounding us? By volume, it consists mainly of nitrogen, oxygen, argon, carbon, and a varying amount of water vapor, as well as small amounts of other gases.
Humans depend heavily on the lower layer of the atmosphere: the troposphere, which is where the weather occurs, with an average thickness of 12 km.
Above that lies the stratosphere, where the ozone layer protects us from harmful solar radiation.
Above that is the mesosphere, the coldest place on Earth, with temperatures averaging -85°C (-121°F).
At an altitude of around 80 km, the thermosphere begins, marking a smooth transition into space.
However, humans have decided that space begins here, at an altitude of around 100 km, where the atmosphere ends and space starts, although the atmosphere extends slightly beyond that.
In this region, we find the ionosphere, the aurora borealis, and the International Space Station (ISS).
The last layer is the exosphere, which rises to about 10,000 km and merges smoothly with outer space.
In this region, atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with each other.
Humans, in their current form, have existed for only about 200,000 years, which is 0.004% of the Earth's history.